Two randomized experiments tested whether simply having your own smartphone nearby affects how well you think. The people studied were undergraduate students at a U.S. university. The first experiment included 520 students (average age 21.1). The second included 275 students (average age 21.3). Before doing memory and reasoning tasks, students were randomly told to leave their phone on their desk, in a pocket or bag, or in another room.
Students whose phones were in another room did better on the thinking tasks than students whose phones sat on the desk (p = .002). This happened even though they did not use their phones and did not report thinking about them. In the second experiment, whether the phone was powered on or off made no difference (p = .83). Being apart from the phone helped memory the most for students who said they relied heavily on their phones (p = .04). One task that measured steady attention over time was not affected at all.
The authors note that the students were all U.S. undergraduates taking part for course credit, so the results may not apply to everyone.
Source: Ward A, Duke K, Gneezy A, et al.. Brain Drain: The Mere Presence of One’s Own Smartphone Reduces Available Cognitive Capacity. Journal of the Association for Consumer Research (2017). doi:10.1086/691462
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